1540s, from Latin tumor "swelling, condition of being swollen," from tumere "to swell" (see thigh).
tumor tu·mor (tōō'mər, tyōō'-)n.
An abnormal growth of tissue resulting from uncontrolled, progressive multiplication of cells and serving no physiological function; a neoplasm.
A swollen part; a swelling.
An abnormal mass of new tissue growth that serves no function in the body. Tumors are usually classified as benign or malignant and are often caused by cancer.